1. Field of the Invention
The present invention relates to an image processing apparatus for encoding an image (image data) and a voice (audio data) and to a method thereof.
2. Related Background Art
A digital video camera and a digital still camera for private use may be given as recording/reproducing apparatuses capable of recording and reproducing an image. Each of these apparatuses executes processing of compressing image data when recording and transmitting the image such as a still image and a moving image.
General standards related to an image compression technology are exemplified such as JPEG (Joint Photographic Experts Group) for the still image and Motion-JPEG, MPEG1 (Moving Picture Experts Group 1), MPEG2 and MPEG4 for the moving image, and recently an examination of new standards such as JPEG2000 is underway.
Further, some of the image compression technologies are capable of encoding a specific region of the image with a higher image quality than in other regions. For example, in case an ROI (Region Of Interest) encoding method is used, an ROI region within a certain picture image can be displayed with the high image quality after being decoded or can be preferentially displayed when being transmitted.
Japanese Patent Application Laid-Open No.2001-230947 discloses a digital still camera, conceived as a camera utilizing such an ROI encoding method, capable of recording and reproducing by effecting the ROI setting of a specified region in a picked-up image and a compression thereof. In the case of performing the ROI setting in the camera, an ROI setting area or object includes a significant and interesting subject in the picture in many cases.
By the way, in the case of applying the ROI setting for a moving image, it is considered that the ROI setting can be done on a frame-by-frame basis in frames forming the moving image. At this time, the frame (ROI frame) including the ROI contains the interesting subject and is therefore considered more significant to a photographer than a frame containing no ROI (which is called a non-ROI frame).
On the occasion of reproducing the moving image data that are encoded including the ROI frame, however, the encoded moving image data are merely decoded and displayed irrespective of the significance described above. Namely, even in a case where the significance is differentiated between the frames, it is impossible to change even a quality of audio data reproduced together with the moving image, in accordance with this significance.